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Unfortunately, the RC records for that area start in 1843http://registers.nli.ie/parishes/1003
The 1857 Griffiths Valuation head of household listing for Ramoghy parish did not show any McKenna records but there were three McBride records. http://www.failteromhat.com/griffiths/donegal/raymoghy.htm
You may want to consider autosomal DNA testing.